the SN74LS90 is a binary counter while the CD4017 is a decimal counter.
To count from zero to 4 the outputs of an LS90 are:
0000, 0001, 0010, 0011, 0100.
It's easier to make the CD4017 count to four by resetting it at count five. Connect Q4 (count five output) to pin15 (MR) of the counter to reset it to zero.
Hi
I am doing a simulation and I don't have a model for the 4017 only the ls90, so I'm trying to work around. I can't even get the LS90 to count in BCD at the moment
Put your clock to input A.
Connect QA to input B.
Connect R0(1) to QA.
Connect R0(2) to QC.
Connect R9(1) to ground.
Connect R9(2) to ground.
Take your three outputs from QA, QB, and QC.
The count will go from 0 to 4 and then back to 0 again: 0,1,2,3,4,0,1,2,3,4,...etc.